Moiré effects are interference patterns of light or other radiation that occurs when sets or patterns of lines, dots, or other repeating features are superimposed on each other. Such interference patterns could be caused by having a multiplicity of the display elements in an array on a display screen. For example, the display may be formed by laminating a number of light emitting diodes (LEDs) to a printed circuit board (PCB), and typically has a regular array of square pixels. In this case, the interference patterns may be caused by the overlaid radiated lights from the sources of LEDs.
Several methods have been disclosed for reducing the moiré effects in displays. For instance, U.S. published applications No. US 2003/0132895 and No. US 2003/0184665 disclose using non-uniformly spaced pixels to avoid moiré effects between display elements such as LCDs, LEDs or TFTs and features of an image being displayed or being detected by a sensor array. U.S. Pat. No. 6,075,581 discloses an optical filter for reducing moiré effects in an LCD or other displays having a matrix-like pixel pattern. Published international application No. WO2004/051354 discloses an electrophoretic display with a two-layer structure in which laminating a top micro-cup layer to a bottom layer at an angle or a less symmetrical micro-cup array is used to avoid formation of undesirable moiré patterns.
Above mentioned methods or display devices employ asymmetrical arrangement of a plurality of pixels to avoid the moiré effects. However, asymmetrical arrangement of the pixels may not be feasible for high resolution displays that requires a large scale integration of pixels. A new display device and a method for reducing moiré effects without changing the arrangement of the pixels are needed.